Transistors are key components of modern integrated circuits. To satisfy the requirements of increasingly faster speed, the drive currents of transistors need to be increasingly greater. Since the drive currents of transistors are proportional to gate widths of the transistors, transistors with greater widths are preferred.
The increase in gate widths, however, conflicts with the requirements of reducing the sizes of semiconductor devices. Fin field-effect transistors (FinFET) were thus developed.
The introduction of FinFETs has the advantageous feature of increasing drive current without the cost of occupying more chip area. However, even though FinFETs have improved short-channel effects (SCE) compared to planar transistors in occupying the same chip are, FinFETs still suffer from SCE. To help control SCE in FinFETs, the fin width of FinFETs is typically narrow. This presents processing and formation difficulties to form such small features. Also in a narrow fin design, the fin is fully or mostly depleted and this diminishes the control of the threshold voltage through substrate bias.
Accordingly, what is needed in the art is a semiconductor device that may incorporate FinFETs thereof to take advantage of the benefits with increased drive currents without increasing the chip area usage while at the same time overcoming the deficiencies of the prior art.